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  • #15903
    Benjamin Bube

    I’m currently running the modems on Channel 3 which is between 93.75khz and 125.00khz. However, another module in my setup working on 5Khz is receiving signals generated through the modems. Every half a second there is one signal identified.

    My question: The Channel Overview states that channel 3 and 2 is best while channels 1 and 4 are not recommended. What about channels 6 and 7? Can these be used without any problems? What disadvantages (range, susceptibility to errors, etc.) can I expect?
    I need a maximum range of 60m-80m underwater with the same data rate.


    Hi Benjamin,

    Any of the channels on the Modem-M64 will work at close range, when getting closer to the range limit (200m) the choice of channel matters.

    Channel 1 has a bit lower signal strength which gives shorter range
    Channel 2-3 has the strongest signal (and is attenuated least in salt water) which is why they are recommended.
    Channel 4 is slightly non-linear, it should work but probably has shorter range and might be more unpredictable.
    Channel 6-7 are good but will be attenuated more in salt-water than channels 2-3 which means shorter range.

    I’m guessing that any of the channels will work fine at 60-80m, so try to find the channel that gives you the least interference.

    Benjamin Bube

    I found the mistake. One of the wires from the modem was too close to said sensitive module. As a result, the power cables of the modem each developed interference when sending. Placing the power cables from the other module a little further removed the problem.
    I got the idea when afterward even the I2C bus said goodbye to the modem or its voltage peaks.

    Many thanks for the fast reply!

Viewing 3 posts - 1 through 3 (of 3 total)

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